Abstract:

This study examines the relationship between fishing activities
of Pacific Northwest albacore fishermen and the availability of albacore.
Tactical responses of troll-boat fishermen were compared to
changes in daily apparent albacore abundance. Tactical responses
included boat aggregation and total applied effort (number of boats)
within a particular area, and net daily distances traveled by individual
boats and the medial center of the fleet. Apparent abundance estimates
were derived from logbook catch records collected during the
1968, 1969 and 1970 seasons.
Fishing power estimates of individual vessels allowed comparisons
to be made of the most successful and least successful boats.
In general, the most successful boats were larger, fished nearer
the fleet center, traveled less net distance each day and caught more
but smaller fish than the less successful boats. The magnitude of the
differences between the most successful and least successful boats
decreased progressively from 1968 to 1970.
Apparent abundance fluctuations were synchronous in separate
areas of the 1968 fishery but not in the 1969 and 1970 fisheries.
Fluctuations tended to be periodic in 1969 and 1970 but not in 1968.
No generalizations as to apparent abundance (patchiness, size of
albacore concentrations) could be determined among years.
Fishermen responded quickly to changes in apparent abundance
during 1968. Boats were highly aggregated on days of high catches,
and dispersed on days of low catches. Fishermen responses during
1969 were one day out of phase with catches. Boats aggregated one
day after days of high catches, indicating that fishermen experienced
difficulty in staying on concentrations of fish. In 1970 fishermen
experienced no difficulty in staying on fish concentrations as record
daily catches were reported.
According to interviews and questionnaires, albacore fishermen
rely heavily on inter-boat communications for planning their daily
fishing tactics. A consequence of this reliance on radio communication
appears to be a greater degree of boat aggregation and less willingness
to scout in areas away from the central fleet area. Areas to the north
and south of the central fleet were shown to have high estimates of
albacore abundance but were exploited by very few boats. Greater
dispersal of the fleet and use of several survey boats are suggested
as a means of increasing the total fishing catch.